Refrigerating apparatus



March 10, 142. R. TULL 2,275,829

REFRIGERATING APPARATUS Filed May 4, 1939 I 4 i; /9 1- WITNESSES: ,3lNVENTOR v POBERT 1'72 77/ ATTORNEY Patented Mar. .10, 1942 robs theevaporator of its then too low. If the room application} in which:

- portions of the tube'broken away;

,UNITED STAT S" PATENT OFFICE-f REFmGEnArnvq APPARATUS Robert 11. Tull,Springfield, Mass, assignor to Westinghouse Electric & ManufacturingCompany; East Pittsburgh, Pa., a corporation of Pennsylvania ApplicationMay 4, 1939, Serial No. 271,636

i 7 Claims. This invention relates to mechanicalrefrig- I crating.apparatus and more especially to means for increasing the efliciency ofrefrigerating apparatus employing a constantly open flowimpediIig-devicer l '1 In mechanical refrigerating apparatus: of the-compressor-condenser-evaporator type employing a constantly openflow-impeding device between the condenser and the evaporator, such asused, for example, in domestic refrigerating apparatus, a 'flooding'ofthe condenser with liquid refrigerant may occur at abnormally low roomtemperatures. At such temperatures an abnormally large'amountpfrefrigerant is condensed in the condenser and accumulate in thelowerpassages thereof. Ifthe evaporator of such a system is, ofrelatively small refrigerant-carrying capacity, such as is usually thecase when the more expensive refrigerants are used, the accumulation ofthe refrigerant in the condenser nor'mal content of refrigeranirandstarves the evaporator. This pro-- duces an uneconomical operation ofthe appara tus because the liquidlevel in the evaporatorjis is verycold, the evaporator may be starved completely of liquid re frigerant,in which case the suction of the compressor produces a vaporization oftheiiquid refrigerant at or within the restricting device therebycooling the evaporator.

One object of the invention, therefore, is to control the quantity ofliquid refrigerant ilrthe evaporator of a mechanicalrfrigerating systememployinga constantly open flow impeding de- 3 vice between thecondenser and the evaporator.

Anotherobject is to provide a condenser for refrigerant vapor whichcondenser'has' a high heat-dissipating value and a low volumetricca-spacity. A further object is to effect a relatively large change inthe vapor condensing area of a .re-'

frigerant condenser", when a relatively small change in the volume ofliquid refrigerant in the condenser occurs.

[ Theseand other objects ate effected by my invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawing'formin'g apart of this g @Fig. 1 is a.side elevationof a condenser with Fig. 2 is an enlarged section of aporti n of g the condenser tube showlng the restricting rod:

I Fig. 3 is a section taken along the line III-III of Fig. 2; and, I a

Fig. 4 is}. diagrammatic view 31 a refrigerator embodying the condenserof this invention.

-' trance end of the capillary tube adjacent the meral I0 represents acondenser and comprises a trally in the tube I I.

tube l I containing a rod l2 of slightly less diameter than the insidediameter of the tube. The rod. l2 may be formed with pinched-out pro-.trusions l3 on its surface to hold the rod lLcen- The condenser isformed by inserting the rod l2 in the tube"l I, bending the tubell,together with the rod I2, into a sinusoidal configuration, and securingcooling -flns H to the outer surface of the tube. The rod l2,

as shown, cccupies the lower portion of the tube' II and is graduallytapered at its upper half.

1 The rod l2, however, maybe of any length and may be tapered in anymanner suited to the operation -of the apparatus. The purpose of the rodI2 is to decrease the volumetric capacity of the tube ll, especially atits lower end without decreasing its esternal diameter upon whichdepends its heat dissipating effect.

The condenser I0 is of particular application in a refrigeratingapparatus of the compressorcondenser, evaporator type employing a con-vstantly open impeding device. betweenthe-condenser and the evaporator.Qne embodiment of restrictor rather than the 30 the electrical conduits23.

'such an apparatus is shown in Fig. 4, and comprises the condenserlllreceiving hot compressed refrigerantvapor at its upper end through atube I 5 from a. compressor 6, which compressor withdraws vaporizedrefrigerant through-a suction tube l-l from an evaporator It! in aninsulated chamber l9. liquid refrigerant from the lower portion of thecondenser I0 through a capillary impedance'tube 2|. A Lscreening device22 is located at the encondenser Ill. The compressor I6 is drivenby anelectric motor 20 which receives power through It will be apparentthatthe insulated chamber I9 is refrigerated by the vaporization of liquidrefrigerant in' the evaporator l8;

The refrigerating apparatus is controlled by a temperature sensitivedevice 24 actuated by a bulb 26 containing an expansible fluid, whichbulb 26 sis in contact with a side-wall of the evaporator 18. Thisdevice 24 controls the temperature of the evaporator 18 betweenpredetermined limits. The volumetric capacity of the condenser I 9 ispreferably smallerthan the volumetric capacity of. the, space normally 0upied by the liquid refrigerantin the evapora r I8. 7 i

The action of -the condenser. Ill on there-'- frigerant-during normaloperation can be divided into three distinct steps, These steps takeplace in-the respective zones A, B, and C, as indicated in Fig. 1. ZoneA comprises the upper portion of the condenseradjacent the inletendthereof in which portion the sensible heat of thesuperheated-refrigerant'is removed.

Zone B comprises the lower central portion of The evaporator is suppliedwith duced to a liquid.

. normal level.

. cooling capacity of the condenser.

the condenser adj acent zone A in which the latent heat of vaporizationof the refrigerant vapor is removed and the refrigerant vapor therebyre- The upper portion of zone B will contain wet refrigerant vapor andvery little 5 liquid refrigerant, the proportion of liquid to vapor willincrease as the refrigerant passes through this zone and the refrigerantwill be entirely liquefied when it reaches the bottom of the 1 zone.

Zone C is the portion of the condenser containing liquid refrigerantwhich is being subcooled below its vaporizing temperature. If thisapparatus is operated in an abnormally cold room, the areas of zone Aand zone B will decrease because the sensible and latent heat is moreactively removed than formerly. Zone C containing liquid refrigerant,therefore, will increase in size to occupy the remainder of thecondenser Ill. 'The rate at which the refrigerant is forced through thecapillary tube 2| into the condenser l8 will also decrease because ofthe decreased pressure of the refrigerant vapor'in zones A and B. Thisdecreased pressure is caused by the decreased temperature of .thecondenser. l0. This decreased flow of refrigerant into the evaporator l8will also aid in increasing the zone C of the condenser. Because of theinsertion of the tapered rod I2 in the lower portion of the condenser,the volume of refrigerant in this portion will be relatively small andcomparatively little liquid refrigerant will be takenfrom the evaporatorIt! so that the liquid refrigerant in the evaporator I8 is moren'earlyat its Y i as It will be observed that the rod I: in the lower portionof the condenser [0 does not decrease the Neither does it substantiallyimpede the flow of liquid refrigerant therethrough because the linearvelocity 40 of the liquid'refrigerant through the tube II is very muchless than the linear velocity of refrigerant vapor because of thegreater density of the liquid. A very beneficial effect also occurs ifthe, refrigerating apparatus is operated in an abnor-' mally warm room.In this case, zones A and B will increase in width and zone C willdecrease and may disappear entirely. The liquid refrigerant normally inzone C is forced into the evap- 5 orator Ill, but since the volume ofliquid in zone C is small because of the presence of the thick end ofthe rod I! in this portion of the tube II,- the level of the refrigerantliquid. in the evaporator ID will rise but little., At the same time aportion of cooling surface which is disproportionately large as comparedto the quantity of refrigerant liquid displaced in zone C is added tozones A and Blwhich added cooling surface aids in condensing therefrigerant vapor in the tube II.

From the above it will be apparent that this invention provides a moreeflicient refrigerating apparatus of the-constantly open restrictor typeand a means for maintaining the liquid levc of G5 the refrigerant in an.evaporator more nearly constant.

While I have shown my invention in but one form, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof T0 various changes and modifications without departing from thespirit thereof, and I desire, therefore, that only such limitationsshall be placed thereupon as are specifically set forth in 7 theappended claims.

What I claim is:

1. In a closed mechanical refrigerating system, the combination of acooling unit'adapted .to evaporate liquid refrigerant, a compressor forwithdrawing refrigerant vapor from said cooling unit and compressingsaid vapor, a condenser for cooling and liquefying said compressedvapor, a

conduit including a fixed flow-impeding orifice for conducting theliquid refrigerant from the 0 condenser to the cooling unit, saidcondenser comprising a refrigerant-carrying tube structure having anentrance and an exit, a substantial portion of said tube structureadjacent its exit end'being of relatively small refrigerant-conductingcross-sectional area, and means for cooling the surface of .said tubestructure, the system being arranged to locate the refrigerant level insaid tub; structure adjacent its exit end during normal operation,said-condenser being formed to have greater heat-abstractingeffectiveness per unit of refrigerant-conducting cross-sectional area ofthe tube structure at the portion adjacent the exit endthan at theportion adjacent the entrance end of the tube structure, whereby a smallchange in the volume of liquid refrigerant in the portion of the tubestructure adjacent the exit end thereof causes a large change .in theeffectiveness of heat abstraction from the refrigerant vapor in the tubestructure, .thereby maintaining the level of the refrigerant liquid inthe cooling unit more nearly constant.

2. In a closed mechanical refrigerating system,

the combination of a cooling unit adapted to evaporate liquidrefrigerant, a compressor for withdrawing refrigerant vapor from saidcooling unit and compressing said vapor, a condenser for cooling andliquefying said compressed vapor, a conduit including a fixedflow-impeding orifice for conducting the liquid refrigerant from thecondenser to the evaporator, said condenser comprising arefrigerant-carrying tube structure having an entrance and an exit, asubstantial portion of said 'tube structure adjacent its exit end beingof smaller refrigerant-conducting cross-sectional area than the portionof said tube structure adjacent its entrance end, and means for coolingthe surface of said tube structure, the system being arranged to locatethe refrigerant level in said tube structure adjacent its exit endduring normal operation, said condenser being formed to have greaterheat-abstracting effectiveness per unit of refrigerant-conductingcross-sectional area of the tube structure at theportion adjacent theexit end than at the portion adjacent the entrance end of the tubestructure, whereby a-small change in the volume of -liquid refrigerantin the portion 'of the tube structure adjacent the exitend thereofcauses a large change in the effectiveness of heat abstraction from therefrigerant vapor in the tube structure,'thereby maintaining the levelofthe refrigerant liquid in the cooling unit more nearly constant.

3. In a closed mechanical refrigerating system, the combination of acooling unit adapted to evaporate liquid refrigerant, a compressor forwithdrawing refrigerant vapor from said cooling unit and compressingsaid vapor, a condenser for cooling and liquefying said compressedvapor, a conduit including a fixed flow-impeding orifice 'for conductingthe liquid refrigerant from the condenser to the cooling unit, saidcondenser comprising a refrigerant-carrying tube of uniformcross-sectional area and having an entrance and an exit, a rod in saidtube adjacent 2,275,829 its exit end, and means for cooling the surfaceof said tube, the system being arranged to cate the refrigerant levelinsaid tube adjacent its exit end during normal operation, said condenserbeing formed to have greater heat-abstracting effectiveness per unit ofrefrigerantof=the tube adjacent the exit end thereof causes a largechange in the effectiveness of heat abconducting cross-sectional area ofthe tube at the portion containing the rod than at the portion adjacentthe entrance end of the tube, whereby a small change in the volume ofliquid refrigerant in theportion of the tube adjacent the exit endthereof causes a large change in the effectiveness of heat abstractionfrom therei'rigerant vapor in the tube, thereby maintaining the level ofthe liquid refrigerant in the cooling unit more nearly constant.

straction from the refrigerant vapor in the tube} thereby maintainingthe level of the refrigerant liquid in the cooling unit more. nearlyconstant.

' 6. In a closed mechanical refrigerating system, the combination of acooling unit adapted to evaporate liquid refrigerant, a compressor-forwithdrawing refrigerant vapor from said cooling unit and compressingsaid vapor, a condenser for cooling and liquefying said compressed vapor, a

4. In a closed mechanical refrigerating system,

, the large end of said rod being adjacent the exit end of the tube,andmeans for cooling the surface of said tube, the system being arrangedto locate the'refrigerant level in said tube adjacent its exit endduring normal operation, said condenser being formed to have greaterheat-abstracting effectiveness per unit of refrigerantconductingcross-sectional area of the tube at the portion adjacent the exit endthan at the portion adjacent the entrance end of the tube. whereby asmall change in the volume of liquid refrigerant in the portion of thetube adjacent the exit end thereof causes a large change in theeflectiveness of heat abstraction from the refrigerant vapor in thetube, thereby maintaining the the cooling unit level of the refrigerantliquid in more nearly constant. a

5. In a closed mechanical refrigerating system, the combination of acooling unit adapted to evaporate liquid refrigerant, a compressor forwithdrawing refrigerant vapor from said cooling unit and compressingsaid vapor, a condenser for cooling and liquefying said compressedvapor,

a conduit including a fixed flow-impeding orifice for conducting theliquid refrigerant from the condenser to the cooling unit,,saidcondenser comprising a refrigerant-carrying tube of uniformcross-sectional area and having. an entrance and an exit, a rod irr onlya portion of said tube adjacent its exit end, and means for cooling thesurface of said tube, the volume in said tube available to therefrigerant being less than-the volume of refrigerant liquid normally inthe cooling unit, the system beingarranged to locate the refrigerantlevel in saidtube adjacent its exit end during normal operation, saidcondenser being formed to have greater heat-abstracting effectivenessper unit of refrigerant-conductingcross- 1 sectional area at theportionofthe tube containing the .rod than at the portion of the tube ad jacentthe entrance end, whereby a small change in the volume of liquidrefrigerant in the portion conduit including a fixed flow-impedingorifice for conducting the liquid refrigerant from the condenser to thecooling unit, said condensercomprising a refrigerant-carryingtube'ofsub- 'stantially uniform cross-sectional area and having anentrance and an exit, a tapered rod in the 1 tube, the large end of saidrod being located near the -,exit end of the tube, the volumetriccapacity of said condenser being'lessthan the volume of refrigerantliquid normally in the cooling unit, and means for cooling the surfaceof I said tube, the system being arranged to locate the refrigerantlevel in said tube adjacent its constant.

exit end during normal operation, said'condenser being formed to havegreater heat-abstracting efiectiveness per unit ofrefrigerant-conducting cross-sectional area of the tube at the portionadjacent the exitend than at theportion adja-' cent the entrance end ofthe tube, whereby a small change in the volume of liquid refrigerant inthe portion of the tube adjacentthe exit end thereof causes a largechange in the effectiveness of heat abstraction from the refrigerantvapor in the tube, thereby maintaining the level of the refrigerantliquid'inthe'cooling unit more nearly 7. In ,a closed mechaiiicalrefrigerating system,

"the combination of a, cooling unit adapted to evaporate liquid refrierant, a compressor for withdrawing refrigeran vapor from said coolingunit and compressing said vapor, a condenser for cooling and liquefyingsaid compressed vapor, a capillary flow-impeding conduit for conductingthe liquid refrigerant from the condenser to the cooling unit, saidcondenser comprising a refrigerant-carrying tube of substantiallyuniform cross-sectional area, said tube having an entrance/and an exit,atapered rod in said tube,

the large end of said rod being located near the exit end of the tube,and means for cooling the surface of said tube, the volumetric capacityof said tube available to the refrigerant therein being lessthan thevolume of refrigerant liquid normally in the cooling unit, the systembein arranged to locate the refrigerant level in said 7 tube adjacentits exit end during normal operation, said condenser being formed tohave greater heat-abstractingeffectiveness per unit ofrefrigerant-conducting'cross-sectional area of the tube at theportion'ad'jacent the exit end than at the portion adjacent the entranceend of the tube structure, whereby a small ch ein theivolume of liquidrefrigerant in the on of the tube adjacent the exit endthereof causes a'large change in the effectiveness of heat abstraction from therefrigerant vapor in the tube, thereby maintaining the level of therefrigerant liquid in the cooling, unit more nearlyconstant;

. v nonna'rn'r'um

